1. Field of the Invention
The present invention relates to a signal measuring method and device for a touch screen, and more particularly, to a signal measuring device and method for a touch screen that compensates the phase delays of the resistor-capacitor (RC) circuits.
2. Description of the Prior Art
A capacitive touch screen determines the locations of touches made by a human body thereon based on changes in detected signals due to its capacitive coupling with the body. When the human touches the screen, noise surrounding the human body also adds to the capacitive coupling between the human body and the capacitive touch screen, and thus causing changes in the detected signals. Moreover, as noise is constantly changing, it cannot be easily determined. When the signal to noise ratio (S/N ratio) is relatively small, a touch may not be detected, or the location of the touch may not be accurately determined.
In addition, as signals may pass through some load circuits, for example, through capacitive coupling, signals received by sensing electrodes of the touch screen will have phase differences with signals before being provided to driving electrodes of the touch screen. If the periods of the driving signals are the same, different phase differences mean that the signals will be received with different delays in time. If said phase differences are not taken into account, then the phases at which signal measuring start will be different and the results will be different. If the measuring results corresponding to different electrodes vary a lot, correct location determination can be challenging.
From the above it is clear that prior art still has shortcomings. In order to solve these problems, efforts have long been made in vain, while ordinary products and methods offering no appropriate structures and methods. Thus, there is a need in the industry for a novel technique that solves these problems.